Before this article, you didn’t even know what CR-39 meant, did you?
What are glasses lenses made of?
One of the first things you notice when you buy glasses is all the types of lenses and addons you can buy. For example, you might have heard about anti-reflective coating for your lenses that can be anything from polycarbonate to CR-39 or even high-index plastic. But what exactly are these types of lenses? Are they? Glass? Plastic? Something completely different?
Short answer: They can be all the above! Most likely, your lenses are made from one of several types of plastic, like CR-39, trivex, polycarbonate and high-index plastic. Glass is rarer today because it's heavier and more fragile than plastic.
Did you think your glasses weren’t made from much? There is a reason they can get so pricey (beyond making sure you look great!).
If you're like most people, you probably don't think about what your lenses are made of but there are many lens materials used in the making of eyeglasses.
Here's a rundown:
Glass
Glass lenses are heavy and thick, making them harder to wear. They also pose a safety risk because they can break into sharp pieces which can cause serious injury to the eyes. Glass lenses are not recommended for children or people with weak facial muscles.
Even though glass lenses have their disadvantages, they offer some benefits that can't be found in plastic lenses: Glass is scratch resistant, and it's easier to clean than plastic. Glass is also excellent for high-index lenses as it can hold its shape very well.
CR-39
CR-39 - The original plastic lens material, CR-39, remains the standard for most frames. These lenses are lightweight and comfortable, but they can still be thicker than higher-end materials in strong prescriptions (4.00 or greater). People with high prescriptions will benefit from high-index lenses' thinner profiles and lighter weights.
Polycarbonate
Polycarbonate is the standard material for children's eyewear because it's extremely durable and lightweight. Most safety glasses are also made of polycarbonate because the material is impact resistant — a critical feature in safety glasses that must provide protection against flying objects or debris. Polycarbonate has one drawback: its optical clarity isn't as great as other materials, so it can cause some distortion when used for vision correction.
Related article: The Best Face Shields to Wear with Glasses!
Trivex
These lenses are similar to polycarbonate in terms of durability and lightweight feel but offer better optics (less distortion). This makes them a great choice for single vision prescriptions and for rimless frames. However, unlike polycarbonate, Trivex cannot be tinted or used for photochromic lenses (which darken when exposed to sunlight).
High-index plastic.
High index plastic is the most expensive material used to make eyeglass lenses. Lenses made from this material are thinner, lighter and more durable than conventional plastic lenses but have similar optical characteristics. High index plastic is best for anyone who wants thin lenses in their prescription eyeglasses but doesn't want the cost of higher priced materials such as polycarbonate.
Conclusion
It is important to note that individual lens designers will have specific lens designs and optical quality can vary even within these lens types. Additionally, lens coating and other glasses add on (edge polish, blue light blockers) can change the experience you feel in your glasses. That said, it is important to seek out information on the different lens materials your optical store offers. We hope this blog is a valuable reference guide for anyone who’s considering a change of frames!
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Spinoza Team